1. Technical Field of the Invention
This invention is related to network switches and routers, and more specifically, to an architecture for providing a single switch image from a stack of network switches.
2. Background of the Art
None of the stacking products available in the existing market provides a single switch/router image, but only offer a facility for a single point of management. In these conventional products, each switch/router performs independently. For example, a MAC address learned in Switch A is not be propagated to Switch B in the same stack. Therefore, when Switch B receives packets destined to the MAC address already learned by Switch A, these packets are flooded by Switch B.
In those stacking products with routing functions, each switch routes packets independently, and each switch requires an independent IP address configuration per routing interface. As a result, a stack of N switches with routing functions behave externally as N independent routers. This causes inefficient use of allocated IP addresses. Additionally, packets routed through the stack may be routed more than once, and hence, experience a longer delay.
Fault tolerance is an important feature of a robust network. Conventional practices include intelligent software agents that continuously monitor redundant links. Other methods of increasing fault tolerance include redundant hardware systems, for example, stacking redundancy which ensures no single point of failure for inter-subnet routing, redundant power supplies, and port aggregation of switches, all of which address keeping critical network services active and accessible. However, these are expensive propositions in both hardware and software, and support resources, and still do not provide a fail-safe system.
What is needed is a single switch/router image for a stack of switches which causes a stack of switches to behave externally as a single switch or a single router, if routing functionality is provided. Such an architecture would provide a high level of fault tolerance without the costs associated with conventional redundant hardware and software systems.